Rhesus macaques closely resemble humans; as such they represent a potentially invaluable animal model for human genetic diseases not amenable to study in rodents. This potential has not been fully realized as the technology for generating null mutants has not been applied to monkeys. The fact that macaques require 4 years before they are able to breed has been a key impediment to the generation of null mutants. One way to circumvent this problem is to disrupt genes in cells and then transfer the nuclei of these cells to enucleated oocytes. If male cells are used, and the gene is on the X chromosome, this procedure should result in the development of a null mutant animal. Kallmann's syndrome is a particularly salient example of a human disease in which null mutant monkeys could provide important new information. Patients with Kallmann's syndrome exhibit two serious abnormalities: 1) they lack olfactory bulbs resulting in anosmia and 2) they do not have LHRH neurons in their brains resulting in hypogonadism. These symptoms are caused by loss of function mutations in the KAL-1 gene. Currently, there is no functional animal model of this disease. We propose three specific aims in this project: 1) to determine the spatial-temporal expression of KAL-1 mRNA in the rhesus macaque; 2) to construct a KAL-1 gene targeting vector; 3) to disrupt KAL-1 in rhesus macaque cells. Successful completion of these three aims would provide preliminary data for a proposal to produce a KAL-1 null mutant rhesus macaque by transferring the nuclei from cells with disrupted KAL-1 genes to enucleated oocytes. The development of this animal model is justified for three reasons. First, a mouse homolog of KAL-1 has not been identified. Second, deletion of this gene in humans is not embryonic lethal but does result in a phenotype that is observable in newborns by noninvasive means. Third, KAL-1 is located on the X chromosome in humans and rhesus macaques. Therefore, it is only necessary to disrupt one copy of this gene, in male cells, to completely abolish KAL-1 expression in the first animal produced. If the long term goals of this project are accomplished, an invaluable model of Kallmann's syndrome would be generated. In addition, a powerful new methodology for the study of human diseases using the rhesus macaque would be established.